The controlled or delayed release of a desired benefit agent (e.g., perfume) is itself not new. Thus, in laundry compositions, for example, a perfume may be combined with water soluble polymer; formed into particles; and added to the composition (see U.S. Pat. No. 4,339,356 or 4,209,417 to Whyte). This method, however, works only for powder or granular detergents because as soon as the polymer is hydrated, the perfume is released.
To prevent release of perfume (or other agents) during a liquid wash product is more difficult. The benefit agent must be stable not only in the heat elevated conditions of the wash, but must also be stable against degradation by water and other harsh chemicals in the wash (e.g., bleach, enzymes, surfactant etc.)
One method to provide these benefits is through microencapsulation. In this process, the benefit agent comprises a capsule core coated completely with a material which may be polymeric. U.S. Pat. No. 4,145,184 to Brain et al. and U.S. Pat. No. 4,234,627 to Schilling et al., for example teach use of a tough coating material which prevents diffusion of the benefit agent (e.g., perfume). The perfume is thus delivered to fabric via the microcapsules and is released by moisture such as would occur when fabric is manipulated.
The above microencapsulation patents thus relate to release of a benefit agent (typically perfume) after surviving a washing process (i.e., process in which protection must be heartier).
Applicants are unaware, however, of the use of microencapsulation technology to protect benefit agents (perfume, silicone moisturizer) in personal wash bar compositions, particularly extruded bar compositions. Specifically, whether due to the shear forces applied when the mixed ingredients are typically passed through a screw/mixer; or the extrusion pressure when billets of soap are extruded from the screw/mixer, no capsule materials are known which can survive the soap making process intact with benefit agent inside. Accordingly, no extruded bars comprising microcapsules are known as far as applicants are aware.
U.S. Pat. No. 5,188,753 to Schmidt et al. teaches detergent compositions containing coated perfume particles. The friable capsule coating used to encapsulate the perfume is the same as used in the capsules of the subject invention. U.S. Pat. No. 5,188,753 further teaches that bars containing the coated perfume particles can be formed (see Example IX at column 12 and claim 6)
It is clear from Example IX, however, that it was absolutely not contemplated to use these capsules in a typical bar extrusion process, i.e., one where ingredients are mixed, chilled (to form soap chips), plodded (in a screw), extruded to form logs, cut and stamped. Rather, the composition is prepared by "gently" admixing coated particles into a soap mixture and formed in a bar in a pin die. Thus, clearly, the inventors themselves contemplated that anything other than formation in a pin die would lead to fracturing of the capsules. The Schmidt patent also is a pure soap bar composition soap.